WO2002003092A1 - Smart antenna with adaptive convergence parameter - Google Patents

Smart antenna with adaptive convergence parameter Download PDF

Info

Publication number
WO2002003092A1
WO2002003092A1 PCT/US2001/041264 US0141264W WO0203092A1 WO 2002003092 A1 WO2002003092 A1 WO 2002003092A1 US 0141264 W US0141264 W US 0141264W WO 0203092 A1 WO0203092 A1 WO 0203092A1
Authority
WO
WIPO (PCT)
Prior art keywords
antennas
convergence parameter
signal
adaptive
convergence
Prior art date
Application number
PCT/US2001/041264
Other languages
French (fr)
Inventor
Yoo Song
Hyuck Kwon
Kyung Min
Original Assignee
Neoreach, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Neoreach, Inc. filed Critical Neoreach, Inc.
Priority to EP01955061A priority Critical patent/EP1410059B1/en
Priority to JP2002508100A priority patent/JP4823469B2/en
Priority to AU2001277266A priority patent/AU2001277266A1/en
Priority to KR1020037000182A priority patent/KR100893718B1/en
Publication of WO2002003092A1 publication Critical patent/WO2002003092A1/en

Links

Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14Systems for determining direction or deviation from predetermined direction
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14Systems for determining direction or deviation from predetermined direction
    • G01S3/16Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived sequentially from receiving antennas or antenna systems having differently-oriented directivity characteristics or from an antenna system having periodically-varied orientation of directivity characteristic
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14Systems for determining direction or deviation from predetermined direction
    • G01S3/28Systems for determining direction or deviation from predetermined direction using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/72Diversity systems specially adapted for direction-finding
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842Weighted combining
    • H04B7/086Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming

Definitions

  • equation (6) empirically as a constant. It is a difficult process to determine the convergence
  • the convergence of the smart antenna in the present invention can be verified through examining equation (9).
  • the update weight vector can be rewritten as
  • the adaptive convergence algorithms as in the present invention perform better in both views of convergence speed and the mean square error at a steady state.

Abstract

A smart antenna (figure 2) i.e., blind adaptive antenna array, is a method and system to suppress multiple access interference and to improve performance, for example in a code division multiple access (CDMA) wireless communications system, including third generation (3g) cdma2000 and wide band (W)-CDMA. A convergence parameter is employed in a smart antenna processor (207). In general, a constant convergence parameter value is empirically determined and used after studying the convergence speed and the steady state mean square error (MSE) or other performance data, such as bit error rate. As the convergence parameter would yield poor performance when the channel environment changes, which is true particularly when a mobile user moves around. In the present invention, the convergence parameter value is adaptively changed and employed in a smart antenna processor (207). Two exemplary methods to update the convergence parameter are described. By employing such an adaptive convergence parameter value, convergence speed can be increased and the steady state MSE can be decreased.

Description

Inventors: Yoo S. Song, Hyuck M. Kwon, and Kyung Y. Min Title: Smart Antenna with Adaptive Convergence Parameter BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION The present invention relates to wireless telecommunications. More particularly, the present invention relates to a novel and efficient smart antenn,a''fbr a code division multiple access wireless communications system. If the smart antenna in the invention is employed at a base station and a desired mobile user moves around high rise buildings, the smart antenna would work more effectively than other existing smart antennas. 2. DESCRIPTION OF THE RELATED ART
In a third generation (3G) wireless communications system, particularly those specified in the wide band (W)-CDMA or the CDMA2000 standard, a base station has an option to employ a smart antenna technology. A smart antenna can suppress interfering signals of different DOAs from the desired users by using spatial diversity. Smart antenna technologies attract much attention these days as they support more users with a high quality of service and high data rates, up to 1.92 mega bits per second (Mbps). Efficient smart antenna schemes have appeared recently. One of them was invented by the present inventors and is in pending U.S. provisional patent application Ser. No. 60/164,552. It would be reasonable to include more realistic environments that have not been considered in the existing literature or inventions. For example, when a mobile user moves around in a downtown of a city with high rise dense buildings, the direction of arrival angles (DOA) from the desired mobile user's multipath signals may change abruptly at a base station receiver due to local scatters around the mobile user. This phenomena is called "edge effects." One of the roles of a smart antenna at a base station is to track the DOAs of dominant multipath signals. The convergence speed of smart antenna weighting coefficients and the DOA tracking capability are critical issues in the design of smart antennas, especially when these edge effects occur frequently. Most of the existing literature or inventions concerning smart antennas do not include these edge effects, and a constant convergence parameter traditionally has been employed. There is still a need for a smart antenna with a fast convergence speed as well as a small mean square error (MSE) under an edge effect environment. Some of the existing literature, e.g., normalized least mean square (NLMS), have considered a time varying adaptive convergence parameter. Also, U.S. Patent No. 5,999,800, Choi, has employed a time varying LaGrange multiplier. However, these existing literature or inventions have employed different optimization criteria or different adaptive schemes from the present invention.
BRIEF SUMMARY OF THE INVENTION A smart antenna that is a blind adaptive antenna array, is a method and system to suppress the multiple access interference and to improve performance of a wireless communications system, including CDMA such as third generation (3G) CDMA2000 and W- CDMA. A parameter is employed in a smart antenna processor. In general, a constant convergence parameter value is empirically determined and used after studying the convergence speed and the steady state MSE or other performance, such as a bit error rate. As the convergence parameter value increases, the convergence speed also increases but the MSE unfortunately increases and vice versa. The smart antenna with a constant convergence parameter would yield poor performance when the channel environment changes, which is true since a mobile user moves around in general. In the present invention, the convergence parameter value is adaptively changed and employed in a smart antenna processor. Two exemplary methods to update the convergence parameter are described. By employing such an adaptive convergence parameter value, the convergence speed can be increased and the steady state MSE can be decreased. Simulation test results confirm that a smart antenna using the adaptive convergence parameter schemes in the present invention shows improved performance for a CDMA system operating under a time-varying fading channel and the edge effects, compared to the existing schemes. In addition, the smart antennas according to the present invention have smaller computation loads than a competitive invention, such as Choi.
In accordance with the invention, there is provided a method of receiving a signal for use in combination with wireless communications. The invention includes the step of receiving a signal in multiple antennas. The received signal is processed utilizing an adaptive convergence parameter. According to one embodiment of the invention, the antennas are a multiple antenna array. According to another embodiment of the invention, the antennas are multiple antennas.
In accordance with one embodiment of the invention, the received signal is processed according to
Figure imgf000005_0001
In accordance with an alternate embodiment, the signal is processed according to
Figure imgf000005_0002
However, the invention is not limited to these two specific algorithms, which are exemplary. The step of processing includes estimating a direction of arrival angle for antennas, the direction of arrival angle being separate from other signal data. Also included is the step of determining a better weighting coefficient.
In accordance with one alternative, the direction of arrival angle is utilized in forward link transmission. In accordance with another alternative, the direction of arrival angle is utilized in reverse link transmission. Other alternatives include that the antennas are in a base station, or are in a mobile station.
In accordance with the invention, there is further provided a system of receiving a signal for use in combination with wireless communications. The system includes at least one signal processor, responsive to a signal received in more than one antenna, having an adaptive convergence parameter. Optionally, the system includes a transmitter connected to the signal processor. Optionally, the system includes a receiver connected to the signal processor.
Optionally, the antennas include multiple antennas. Optionally, the signal processor includes a filter, the filter having the adaptive convergence parameter. Optionally, the signal processor includes a measurement of a direction of arrival angle for antennas, the measured direction of arrival angle being separate from other signal data.
Alternatively, the signal processor further includes a determination of a better weighting coefficient. Alternatively, the measured direction of arrival angle has been obtained from a reverse link transmission. According to one embodiment, the system includes a base station, wherein the antennas are in the base station. According to another embodiment, the system includes a mobile station, wherein the antennas are in the mobile station. These and other objects, features and advantages of the present invention are readily apparent from the following drawings and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The features, objects, and advantages of the present invention will become more apparent from the detailed description set forth below when taken in conjunction with the drawings in which like reference characters identify correspondingly throughout and wherein:
FIG. 1 is an example model of a complex pseudonoise (PN) spread transmitter for a CDMA system configured in accordance with one embodiment of the present invention;
FIG. 2 is an overall block diagram of a base station receiver configured in accordance with one embodiment of the present invention;
FIG. 3 shows a flow chart of a smart antenna processor with an optimum convergence parameter algorithm configured in accordance with one embodiment of the present invention;
FIG. 4 shows a flow chart of a smart antenna processor with a heuristic convergence parameter algorithm configured in accordance with one embodiment of the present invention; FIG. 5 shows some simulation DO A estimate results versus iteration with a single realisation, indicating that the smart antennas configured in accordance with one embodiment of the present invention have faster convergence speed and smaller mean square error;
FIG. 6 shows two curves separately from FIG. 5 for the two adaptive convergence algorithms in the present invention; and FIG. 7 shows some simulation bit error rate (BER) results versus the number of edge effect occurrences in a frame of 20 ms, indicating that the smart antenna configured in accordance with one embodiment of the present invention shows slightly better performance under edge effects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention considers a reverse link from a mobile to a base station, although the invention is equally applicable to a forward link beam-forming process, such as in a CDMA wireless communications system. In addition, although the transmitter and receiver in the example is similar to a CDMA2000 system for a demonstration purpose, the present invention is also applicable to other CDMA systems, such as a W-CDMA system when the weight vector in a smart antenna is adaptively generated with a convergence parameter.
FIG. 1 is an example transmitter spread by a complex PN sequence for a CDMA system
like a CDMA2000 or a W-CDMA. The I-channel input data stream 101 dn'{k) in the pilot
channel is either 1 or a sequence of ±1 known pattern, and the Q-channel input data stream 105
d (k) in a traffic channel is a random sequence of ±1 where k denotes the code symbol index
and n the user index. The pilot amplitude 103 AQ is set to 1 and Walsh code 107 b (z) to ±1
where i denotes the chip index. Each code symbol is spread into G chips where G is called the
spreading factor (SF). The I and Q data are complex PN spread with 108 an (i)=an I(i)+ja®(i) .
The PN spread signal can be written as
(A (k)bi (0 + Jd° (k)b° (i)} {ai (0 + ja° (i)} , {k-l)G ≤ i ≤ kG (1)
where y is the positive square root of (-l). The equivalent lowpass signal after pulse shaping filter
109 H(f) is denoted as sn'(t) + js®{t) . The transmitted signal 111 sn(t) from the n-th user is written as
sH ( = Tte{fp(sΛ' (0 + jsn Q ( V2* } (ι-l)Te ≤t ≤iTc (2)
where t is the time variable, Refzj is the real part of complex number z, P is the transmitted power, fc is the carrier frequency, and e is the exponential operator, and Tc is the chip time interval.
FIG. 2 shows an example receiver block diagram with a smart antenna for a CDMA reverse link. The present invention improves performance of the smart antenna in FIG. 2. The
number of antenna array elements 201 is M. The array element spacing d is set to λ/2, where λ is a wavelength equal to the speed of light divided by the carrier frequency. The signals arrive substantially identically at each element because the maximum distance between elements is less
than or equal to (M-l)λ/2, which is only 31.6 cm when carrier frequency is 1.9 GHz and M-5.
The relative phase difference due to the array element spacing between the reference and the m- th element output is e-jn(m-i)dsmθ/λ ^ =^ ^ M w ere øis the DOA of the desired signal. The first element is
set to be a reference element. The antenna array response vector a(θ) can be written as
a{θ) = [l e~jπshlθ ■ ■■ e- -»π θf (3)
where Tis the transpose operator. The received signal at the m-th element, m=l, ..., M, can be written as
Figure imgf000009_0001
where n, «/,„(/), ι,n(t), and θιιn(t) are respectively the multipath delay, amplitude, phase and DOA of the /-th path from user n, n=l, ..., N, and nm (t) is the additive white Gaussian noise 203 (AWGN). The output of each element is frequency down converted. The baseband filter outputs 205 are sampled every chip interval and denoted as xιtm(i). The smart antenna processor 207 takes pre-PN processing chip vectors xj(i) and post-PN processing chip vectors yj(i). The pilot-aided channel estimates 211 are obtained by taking the average of the post PN despread 209 samples over an interval of Np chips. The spatial and temporal RAKE combining 213 is performed over m-1, ..., M antenna elements and 1=1, ..., L fingers. The soft decision variable u(k) 111 in FIG. 2 is fed into either a Viterbi convolutional decoder 215 in soft decision 217 or hard decision 219 value for the k-th code symbol decoding if a convolutional encoder is employed at the transmitter.
The present invention preferably employs a smart antenna based on maximum output power criteria, such as used in Choi. Other criteria can be used as long as the smart antenna
weight vector is updated with an adaptive algorithm. A constant convergence parameter μ was
used in Choi or other existing algorithms.
A cost function based on a maximum output power criteria can be written as
J(w(k)) = wH (k)Ryy(k)w(k) + 7(k) -- (k)w(k)) (5)
where wH(k) is the Hermition, that is, conjugate and transpose of Mby 1 weight vector w(k), y(k) is a post PΝ despread observed Mby 1 vector and the m-th component, ym(k) is the sum of post PΝ despread samples ym(i) in FIG. 2 over G chip intervals, Ryy(k) is an Mby M auto-correlation
matrix ofy(k), and γ(k) is a LaGrange multiplier for constraint wH(k)w(k)=l. The finger index / is
dropped for brevity from now on. And k denotes the update time index, called iteration or snapshot index. In the preferred embodiment, the update rate is set to a code symbol rate, although the update rate can be faster than the code symbol rate. At each iteration, or snapshot,
the weight vector is updated as w(k+l)=w(k)-l/2μVJ(w(k)) where VJ(w(k)) is the gradient vector
for cost function J(w(k)) given in equation (5) with respect to w(k), and μ is a convergence parameter. The updated weight vector can be written as w(k + 1) = (l - μγ{k))w{k) + μy(k)z(k) (6)
where z(k)=yH (k)w(k) is the adaptive filter output and Ryy(k) is approximated asy^fyy^ ). (It was
claimed in the Choi device that if LaGrange multiplier γ(k) is updated every snapshot under
constraint wH(k)w(k)=l instead of using constant value γ, then γ(k) is converged into the maximum eigenvalue of Ryy as iteration goes on.)
Conventionally known adaptive filters determine the convergence parameter μ in
equation (6) empirically as a constant. It is a difficult process to determine the convergence
parameter μ when the channel environment keeps changing. Convergence parameter value μ
influences the convergence speed of an adaptive algorithm. If μ is small, then the convergence
speed is low but the excess of mean square error is small, and vice versa. The present invention
updates the convergence parameter μ(k) adaptively, preferably during every snapshot instead of
employing a constant convergence parameter all the time. The present invention fixes the
LaGrange multiplier γ(k) as a constant value equal to the maximum eigenvalue of Ryy, that is,
γ(k)=M because adaptive γ(k) does not change the convergence speed. Therefore, the cost
function in equation (5) is changed as
J(w(k)) = w" (k)Ryy (k)w(k) + γ(l - wH (k)w(k)) (8)
for the present invention. And the new weight vector wβ+1) in equation (6) is found as
w(k + 1) = (l - μ{k)γ )w(k) + μ(k)y(k)z(k) (9)
by finding the gradient VJ(w(k) and substituting it into the update equation: wfi+l)=ηv(k)-
1/2 μ(k) VJ(w(k)). Also, by taking the derivative of the cost function in equation (8) with respect
to μ(k) and making it equal to zero, an optimum adaptive convergence parameter μ k) to minimise the cost function can be found as
Figure imgf000012_0001
where \z(k) | is the magnitude of complex array output z(k) and y(k) is the inner product of the
observed post PN despread vector y_(k).
A heuristic adaptive convergence parameter μ(k) can be found as
Figure imgf000012_0002
The heuristic adaptive convergence parameter in equation (11) is reasonable. When the weight
vector w(k) does not match with the channel array response vector a(θ(k)) of equation (3), the
array output z(k)=yH(k)w(k) would have little power and the adaptive convergence parameter
μ k) would be large and the convergence step would be large at iteration k and search processing
can be sped up. When weight vector w(k) matches with channel array response vector a(θ(k)),
the array output z(k)=yH(k)w(k) would have maximum output power equal to M2 and the adaptive
convergence parameter μ(k) would be small and the excess mean square error would be small.
The convergence of the smart antenna in the present invention can be verified through examining equation (9). The update weight vector can be rewritten as
w(k + 1) = [1 - μ(k)γ]w(k) + μ(k)y(k)z(k) (12)
= [7(1 - μ(k)γ) + μ{k)Ryy (k)]w(k) (13)
= [<2{/(l - μ(k)y) + μ(k)A)QH f w(0) (14)
= β[ 7(1 - μ(k)γ) + μ(k)A]k+] QH w(0) (15) where Q is a unitary matrix satisfying Ryy-QΛζf1, A is a diagonal matrix with the z'-th diagonal element equal to the z'-th largest eigenvalue of matrix Ryy, and w(0) is the initial weight vector set to (1, 1, ..., if. The bracket matrix raised with power (k+1) in equation (15) is a diagonal matrix
and diagonal values decrease as iteration goes on if
Figure imgf000013_0001
Therefore, γis set to
λmax=M.
For a comparison purpose, a Wiener filter is re-examined for the smart antenna
application. The Mby 1 PN-despread output vector is represented as y(k)=bιa(θι)+n(k) where b]
and a(θι) are a data bit of ±1 and an array response vector of DOA θj from user 1, respectively,
and n(k) is the interference plus thermal noise vector. The desired adaptive filter output or the
reference signal can be set to
Figure imgf000013_0002
for a Wiener filter. Ideally, the cross correlation vector £ can be written as
p = E(d*y(k)) (16)
= H φι)a ι)Ek(θ,) + )) . (17)
= Ma(θ ) . (18)
Then, the ideal Wiener solution can be obtained as w = Ryy~l£ (19)
=[QΛQHJ-'Ma(θ1) (20)
=MQA]QHa(θ1) (21)
=M [qιt ..., q_M] fλf', ..., AM 1] [ i, ..., q_Mf g_ι M (22)
Figure imgf000013_0003
qMJ fλf1, ...,' λM '!] [1, 0, ..., Of (23)
Figure imgf000013_0004
Figure imgf000014_0001
where a(θι)=gι -[M was used in equation (22). The array response vector a(θj) in equation (26)
can be obtained by multiplying the conjugate of the pilot channel estimation to compensate the fading phase distortion and keep the DOA components only at each element. The simulation test results for Wiener filter are compared to those obtained with the present invention by using the pair of equations (9) and (10) for optimum adaptive convergence parameter and the pair of equations (9) and (11) for a heuristic adaptive convergence parameter algorithm.
For comparison, other typical adaptive algorithms were also tested through simulation and compared with the present invention. For example, least mean square (LMS), normalized least mean square (NLMS), recursive least square (RLS), minimum mean square error (MMSE) proposed by the present inventors, the Choi device, and an adaptive algorithm with perfect weight vector set to the array response vector were tested through simulation. Instantaneous matrix Ryy(k)=y_(k)yH (k) was used for all adaptive algorithms if the algorithm requires Ryy. This approximation is reasonable for an urban environment when the channel is subject to edge effects and multipath fading environments. The Wiener filter is an optimum solution under a pure AWGN stationary environment. However, the Wiener solution may not be the best under a channel subject to frequent edge effects. In addition, even if a perfect weight vector is employed, some degradation is expected due to the presence of a noise vector. Parameters for simulation test environments, including one embodiment of the present invention, are listed in TABLE 1. TABLE 1. Parameters used for simulation test environments.
Figure imgf000015_0001
FIG. 3 and FIG. 4 show flow charts for an optimum adaptive algorithms and a heuristic adaptive convergence parameter algorithm, respectively, in the present invention, which use pairs of equations {(9), (10)} and {(9), (11)}, respectively. FIG. 3 illustrates an adaptive convergence algorithm for a smart antenna processor.
At step 301, the system makes an initial guess at weight vector w(0) set to (1, ...1), and
fixes the LaGrange multiplier γ at λmax (which is equal to M) At step 303, a new signal is
received and the post PN despread signal is observed and taken as the new signal vector (k). Steps 305 and 307 correspond to the smart antenna processor (207 in FIG. 2). At step 305, the array output is determined as the complex array output z(k), and an optimal adaptive
convergence parameter μ (k) is determined (according to equation (10)). At step 307, the new
weight vector w(k+l) is determined (according to equation (9)).
FIG. 4 illustrates an alternative example of an adaptive convergence algorithm for a smart antenna processor; this example is heuristic.
At step 401, the system makes an initial guess at weight vector and fixes the LaGrange multiplier as a constant. At step 403, a new signal is received and the post PN despread y_(k) is obtained. At step 405, the array output is determined as the complex array output z(k), and an
adaptive convergence parameter μ (k) is determined (according to equation (11)). At step 407, the new weight vector w (k+1) is determined (according to equation (9)).
FIG. 5 shows a single realization of the DOA estimates versus iteration (i.e., snapshot) index k for different adaptive algorithms. The results for the LMS, NLMS, and RLS were also tested through simulation, but not shown in FIG. 5. These algorithms track the total angle of the input including the fading phase, thermal noise phase, and the DOA, while the two adaptive convergence parameter algorithms in the present invention (optimum mu and heuristic mu), the MMSE in the co-pending US patent disclosure by the present inventors, Wiener, and Choi's algorithms can track the DOAs separately. Each snapshot takes G number of chips to update the weight vector since snapshot rate was set to code symbol rate. The edge effect, or DOA of the desired signal jumps from 0 ° to 40° at the 70-th iteration. The initial weight vectors for all
algorithms were set so that the estimated DOA is equal to 0 " before the first edge effect
occurrence at the 10-th iteration. FIG. 5 indicates that the smart antenna algorithm has a fast convergence speed and a small mean square error. Also, FIG. 5 indicates that the two adaptive convergence algorithms in the present invention take only four iterations while Choi's invention takes twenty-two iterations to reach
90% of the target DOA equal to 40 °. The Wiener algorithm can converge faster than the present
invention, but shows large ripples in a steady state. Therefore, the adaptive convergence algorithms as in the present invention, perform better in both views of convergence speed and the mean square error at a steady state.
FIG. 6 shows two curves from FIG. 5 for the two adaptive convergence algorithms in the present invention (optimum mu and heuristic mu). The angle tracking behavior of the optimum adaptive convergence parameter algorithm in equations (9) and (10) is slightly faster than that of the heuristic adaptive convergence parameter algorithm in equations (9) and (11). However, the MSE of the optimum convergence parameter algorithm can be slightly larger than of the
heuristic adaptive convergence parameter algorithm because the optimum μ(k) is to minimize the
cost function J(w(k) in equation (8) and is not necessary to minimize the MSE.
FIG. 7 shows the uncoded BER performance of a CDMA system with smart antennas versus the number of edge effect occurrences in a frame interval of 20 ms by using the different adaptive algorithms. The BER performances of all algorithms are close to each other. The adaptive convergence algorithms in the present invention and Choi's algorithm are almost the same and are slightly better than others. The BER of the algorithm with the perfect weight vector matches the theoretical BER.
TABLE 2 is the list of the number of computations per snapshot for each smart antenna where M is the number of antenna array elements configured in accordance with one embodiment of the present invention that shows smaller number of computations per snapshot than Choi's device. TABLE 2 summarises the number of complex computations per snapshot. The RLS requires the most and Wiener, the least number of computations per snapshot. The number of computations per snapshot for the adaptive convergence algorithm in the present invention is less than Choi's device.
TABLE 2
Figure imgf000018_0001
Finally, an estimate θ of the DOA from the desired user signal can be obtained with the adaptive algorithms in the present invention. The weight vector w(k) would approach to the array response vector a(θ) in equation (3) when the smart antenna tracks the direction of the arrival angle from the desired signal and the weight vector is normalised every iteration by the first element of the weight vector. The estimate of the DOA can be obtained as
Figure imgf000019_0001
where sin '( ) is the arcsine function, z is the angle of z, M> (k) is the second element of the
weight vector w(k) at iteration k, and π is the radian angle for 750°. The DOA estimate θ
obtained through the present invention can be employed for the other way beam forming, i.e., forward link beam forming. A forward link implies the channel from a base station to a mobile station, and a reverse link is a channel from a mobile to a base station. The weight vector w(k) obtained with the present invention through a reverse link can be used for a forward link beam forming from a transmitter in the base station to a receiver in the desired mobile receiver after compensating the phase rotation due to the carrier frequency difference between the forward and reverse link. Therefore, performance of the forward link can be also improved with the present invention. TABLE 3 is a list of the mean square errors for each smart antenna under edge effects including transient periods, and the steady state mean square errors in accordance with one embodiment of the present invention, that shows a comparable mean square error to the
competitive invention. TABLE 3 lists the MSE between DOA estimate θ and true DOA θ for
several different DOA tracking algorithms for two cases: (1) simulation test intervals including transient periods, and (2) only steady state portions. The steady state MSE was obtained by averaging the squares of errors every edge effect interval from the iteration point whose tracking angle reaches 90% of the target angle first time to the next edge effect. Ten, one hundred, and one thousand number of edge effects were randomly generated every 20 ms for simulation tests. The present invention and Choi's device have a smaller steady state MSE than others, and Wiener has the largest steady state MSE.
TABLE 3. Mean Square Error (MSE) = El θ -θ\
In conclusion, a smart antenna having either optimum or heuristic adaptive convergence parameter algorithms of the present invention, can be more effective than conventional systems under an edge effect environment particularly for a CDMA reverse link. The adaptive convergence parameter algorithms in the present invention show much better DOA tracking capability and slightly better bit error rate performance than a conventional device. Furthermore, the number of computation loads per snapshot for the heuristic adaptive convergence parameter algorithm is smaller than that in the conventional device.
While the preferred mode and best mode for carrying out the invention have been described, those familiar with the art to which this invention relates will appreciate that various alternative designs and embodiments for practicing the invention are possible, and will fall within the scope of the following claims.

Claims

What is claimed is:
1. A method of receiving a signal for use in combination with wireless communications, comprising the steps of:
(A) receiving a signal in a plurality of antennas;
(B) processing the received signal utilizing an adaptive convergence parameter.
2. The method of claim 1 , wherein the plurality of antennas is a multiple antenna array.
3. The method of claim 1, wherein the plurality of antennas are multiple antennas.
4. The method of claim 1 , wherein the received signal is processed according to
Figure imgf000022_0001
5. The method of claim 1 , wherein the signal is processed according to
Figure imgf000022_0002
6. The method of claim 1, wherein the processing step includes estimating a direction of arrival angle for antennas, said direction of arrival angle being separate from other signal data.
7. The method of claim 1, further including the step of determining a better weighting coefficient.
8. The method of claim 6, further comprising the step of utilizing the direction of arrival angle in forward link transmission.
9. The method of claim 6, further comprising the step of utilizing the direction of arrival angle in reverse link transmission.
10. The method of claim 1 , wherein the antennas are in base station.
11. The method of claim 1, wherein the antennas are in a mobile station.
12. A system of receiving a signal for use in combination with wireless communications, comprising:
(A) at least one signal processor, responsive to a signal received in a plurality of antennas, having an adaptive convergence parameter.
13 The system of claim 12, further comprising the plurality of antennas.
14. The system of claim 13, wherein the plurality of antennas includes a multiple antenna array.
15. The system of claim 12, further comprising a transmitter connected to the at least one signal processor.
16. The system of claim 12, further comprising a receiver connected to the at least one signal processor.
17. The system of claim 13 , wherein the plurality of antennas includes multiple antennas.
18. The system of claim 12, wherein the at least one signal processor includes a filter, the filter having the adaptive convergence parameter.
19. The system of claim 12, wherein the adaptive convergence parameter in the at least one signal processor is substantially:
Figure imgf000023_0001
20. The system of claim 12, wherein the adaptive convergence parameter in the at least one signal processor is substantially:
Figure imgf000023_0002
21. The system of claim 12, wherein the at least one signal processor includes a measurement of a direction of arrival angle for a plurality of antennas, said measured direction of arrival angle being separate from other signal data.
22. The system of claim 12, wherein the at least one signal processor further includes a determination of a better weighting coefficient.
23. The system of claim 21, wherein the measured direction of arrival angle has been obtained from a forward link transmission.
24. The system of claim 19, wherein the measured direction of arrival angle has been obtained from a reverse link transmission.
25. The system of claim 13, further comprising a base station, wherein the plurality of antennas are in the base station.
26. The system of claim 13, further comprising a mobile station, wherein the plurality of antennas are in the mobile station.
PCT/US2001/041264 2000-07-05 2001-07-05 Smart antenna with adaptive convergence parameter WO2002003092A1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
EP01955061A EP1410059B1 (en) 2000-07-05 2001-07-05 Smart antenna with adaptive convergence parameter
JP2002508100A JP4823469B2 (en) 2000-07-05 2001-07-05 Smart antenna using adaptive convergence parameters
AU2001277266A AU2001277266A1 (en) 2000-07-05 2001-07-05 Smart antenna with adaptive convergence parameter
KR1020037000182A KR100893718B1 (en) 2000-07-05 2001-07-05 Smart Antenna with Adaptive Convergence Parameter

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US09/610,470 2000-07-05
US09/610,470 US6369757B1 (en) 2000-07-05 2000-07-05 Smart antenna with adaptive convergence parameter

Publications (1)

Publication Number Publication Date
WO2002003092A1 true WO2002003092A1 (en) 2002-01-10

Family

ID=24445129

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2001/041264 WO2002003092A1 (en) 2000-07-05 2001-07-05 Smart antenna with adaptive convergence parameter

Country Status (6)

Country Link
US (1) US6369757B1 (en)
EP (1) EP1410059B1 (en)
JP (1) JP4823469B2 (en)
KR (1) KR100893718B1 (en)
AU (1) AU2001277266A1 (en)
WO (1) WO2002003092A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100784244B1 (en) 2006-08-07 2007-12-11 주식회사 케이티프리텔 Terminal and method for dynamic setting communication option
US8738103B2 (en) 2006-07-18 2014-05-27 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020006121A1 (en) * 2000-04-27 2002-01-17 Dileep George Adaptive diversity combining for wide band code division multiple access (W-CDMA) based on iterative channel estimation
US7085240B2 (en) * 2000-10-03 2006-08-01 Kathrein-Werke Kg Directed maximum ratio combining and scheduling of high rate transmission for data networks
US6876337B2 (en) 2001-07-30 2005-04-05 Toyon Research Corporation Small controlled parasitic antenna system and method for controlling same to optimally improve signal quality
KR100591700B1 (en) * 2001-10-06 2006-07-03 엘지노텔 주식회사 Method for searching signal path in array antenna system, Apparatus for the same
US7272167B2 (en) * 2002-02-06 2007-09-18 Neoreach, Inc. PN code chip time tracking with smart antenna
US7035319B2 (en) * 2002-07-31 2006-04-25 Freescale Semiconductor, Inc. Method and apparatus for determining whether a received signal includes a desired signal
KR100513598B1 (en) * 2002-11-27 2005-09-09 한국전자통신연구원 Normalizing apparatus for adaptive beamforming in smart antenna receiving system
US7161973B2 (en) * 2002-12-17 2007-01-09 Sbc Properties, L.P. Pilot aided adaptive minimum mean square interference cancellation and detection
WO2004059793A1 (en) * 2002-12-31 2004-07-15 Zte Corporation Smart antenna, method and device for forming
US7385617B2 (en) 2003-05-07 2008-06-10 Illinois Institute Of Technology Methods for multi-user broadband wireless channel estimation
US7079870B2 (en) * 2003-06-09 2006-07-18 Ipr Licensing, Inc. Compensation techniques for group delay effects in transmit beamforming radio communication
KR100663442B1 (en) * 2003-08-20 2007-02-28 삼성전자주식회사 Apparatus and method for receiving signal in mobile communication system using adaptive antenna array scheme
US7400692B2 (en) * 2004-01-14 2008-07-15 Interdigital Technology Corporation Telescoping window based equalization
GB0402102D0 (en) * 2004-01-30 2004-03-03 Mitel Networks Corp Method for detecting echo path changes in echo cancellers
TWI355112B (en) * 2007-06-14 2011-12-21 Asustek Comp Inc Method and system for setting smart antenna
US20160204508A1 (en) * 2015-01-12 2016-07-14 Altamira Technologies Corporation Systems and methods for controlling the transmission and reception of information signals at intended directions through an antenna array
CN108572347A (en) * 2017-03-09 2018-09-25 上海交通大学 The two-dimentional angle-measuring method of face battle array based on communication signal channel condition responsive information and system

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5524023A (en) * 1994-04-28 1996-06-04 Nec Corporation Interference cancellation using power-inversion adaptive array and LMS adaptive equalizer

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4931977A (en) * 1987-10-30 1990-06-05 Canadian Marconi Company Vectorial adaptive filtering apparatus with convergence rate independent of signal parameters
JPH09214236A (en) * 1996-02-06 1997-08-15 Mitsubishi Electric Corp Interference wave suppression device
JP3482810B2 (en) 1996-04-18 2004-01-06 崔 勝元 Array antenna and its design method, signal processing method with array antenna, and signal transmitting / receiving apparatus and method using the same
ITMI981280A1 (en) * 1998-06-05 1999-12-05 Italtel Spa RAPID CONVERGENCE SPACE AND TEMPORAL RQUALIZATION METHOD FOR THE CANCELLATION OF STATIONARY AND NON-STATIONARY ISOFREQUENTIAL INTERFERENTS
US6501747B1 (en) * 1998-08-20 2002-12-31 Metawave Communications Corporation Manifold assisted channel estimation and demodulation for CDMA systems in fast fading environments

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5524023A (en) * 1994-04-28 1996-06-04 Nec Corporation Interference cancellation using power-inversion adaptive array and LMS adaptive equalizer

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8738103B2 (en) 2006-07-18 2014-05-27 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US9099773B2 (en) 2006-07-18 2015-08-04 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US9899727B2 (en) 2006-07-18 2018-02-20 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US10644380B2 (en) 2006-07-18 2020-05-05 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US11031677B2 (en) 2006-07-18 2021-06-08 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US11349200B2 (en) 2006-07-18 2022-05-31 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
US11735810B2 (en) 2006-07-18 2023-08-22 Fractus, S.A. Multiple-body-configuration multimedia and smartphone multifunction wireless devices
KR100784244B1 (en) 2006-08-07 2007-12-11 주식회사 케이티프리텔 Terminal and method for dynamic setting communication option

Also Published As

Publication number Publication date
EP1410059A1 (en) 2004-04-21
JP2004503147A (en) 2004-01-29
KR100893718B1 (en) 2009-04-17
US6369757B1 (en) 2002-04-09
EP1410059A4 (en) 2010-07-28
AU2001277266A1 (en) 2002-01-14
KR20030053500A (en) 2003-06-28
EP1410059B1 (en) 2012-08-15
JP4823469B2 (en) 2011-11-24

Similar Documents

Publication Publication Date Title
WO2002003092A1 (en) Smart antenna with adaptive convergence parameter
EP1499037B1 (en) Apparatus and method for receiving data in a mobile communication system using an adaptive antenna array scheme
JP2003521822A (en) Practical space-time wireless method for improving CDMA communication capacity
CA2333609A1 (en) Adaptive transmitter/receiver
US20070189362A1 (en) Method and system for channel estimation, related receiver and computer program product
KR100663442B1 (en) Apparatus and method for receiving signal in mobile communication system using adaptive antenna array scheme
JP4520985B2 (en) Apparatus and method for receiving data in a mobile communication system using an adaptive antenna array system
JP4339354B2 (en) Apparatus and method for receiving signal in mobile communication system using adaptive antenna array system
US6993064B2 (en) Multi-user receiving method and receiver
KR100311513B1 (en) Adaptive Beamforming Method
KR20020039424A (en) High Performance Space-Time Array Receive System and Method Using Fading Rate Indicator
Fujii Path diversity reception using SMI steering vector arrays and multi-trellis Viterbi equalizer
Wang et al. Adaptive arrays for high rate data communications
KR101043759B1 (en) Method for deciding lms error for lms algorithm application of system using smart antenna
Kudoh et al. Performance comparison on wireless access scheme for high data rate transmission in mobile radio
Yoshii et al. Adaptive spatial and temporal optimal receiver using adaptive array antenna

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE TR BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWE Wipo information: entry into national phase

Ref document number: 1020037000182

Country of ref document: KR

WWE Wipo information: entry into national phase

Ref document number: 2001955061

Country of ref document: EP

WWP Wipo information: published in national office

Ref document number: 1020037000182

Country of ref document: KR

WWP Wipo information: published in national office

Ref document number: 2001955061

Country of ref document: EP